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Magnesian calcite and dolomite in the Krečana marble (Bukulja–Venčac area, central Serbia): A possible modification for geothermometry application purposes?
No full textThe chemical compositions and formation temperatures of magnesian calcite and dolomite were estimated by using the combination of chemical analysis, crystallographic parameters, and a plethora of various diagrams and mathematical calculations. This study presents an example of the calculated crystallo-chemical formula (Ca0.960Mg0.039Fe0.001)CO3, obtained
from chemical analysis on a representative marble sample from the Bukulja–Venčac area in central Serbia. Substituting CaCO3 with MgCO3 and FeCO3 in dolomite adds approximately 3–5 mol. %, enhancing the classification and indicating that it is more accurately identified as magnesium-excess dolomite. The estimated formation temperature of magnesian calcite (1) is approximately 528 ◦C, whereas magnesian calcite (2) forms at about 341 ◦C. The ~187 ◦C difference corresponds to ~3.28 mol. % MgCO3 (~7.18% dolomite), reflecting
the distinction between magnesian calcite (1) and magnesian calcite (2). Considering the presence of the submicroscopic intergrowth and exsolution of dolomite within magnesian calcite (1), which are further subdivided in magnesian calcite (2), the estimated formation temperature of ~341 ◦C appears to be more realistic. The synthesis of the results suggests that this combined method could be helpful in the geothermometry of marble samples
after the treatment with acetic acid. However, despite the promising results, additional experiments are necessary to validate the proposed modified geothermometry approach.Supplementary material: [https://cer.ihtm.bg.ac.rs/handle/123456789/9122
Comparative study of antimicrobial activity of silica-based nanohybrids functionalized with 5-aminosalicylic acid: toward reduced silver usage
No full textIn this study, we report the synthesis, characterization, and antimicrobial evaluation of two silica-based hybrid nanocomposites: SiO2 functionalized with 5-aminosalicylic acid (5-ASA), and its silver-decorated counterpart, SiO2/5-ASA/Ag. The organic ligand 5-ASA was covalently anchored onto the surface of amorphous silica nanoparticles, forming interfacial charge-transfer (ICT) complexes capable of visible-light absorption, as confirmed by UV–Vis diffuse reflectance spectroscopy and supported by DFT/TD-DFT calculations. The subsequent deposition of silver nanoparticles resulted in the formation of plasmonic nanohybrids with enhanced light-harvesting properties. The materials were extensively characterized using FTIR, TGA/DTA, XRD, HRTEM/EDX, and DRS techniques. Their antimicrobial activities were assessed against Escherichia coli, Staphylococcus aureus, and Candida albicans using time-resolved CFU assays at multiple concentrations. Both hybrids demonstrated significant antimicrobial performance; however, notably, the silver-free SiO2/5-ASA sample exhibited potent bactericidal activity, particularly against S. aureus, even at low concentrations. This finding suggests that the presence of –NH2 groups from the 5-ASA ligand contributes to antimicrobial action via interactions with bacterial cell walls, highlighting the potential for silver-free nanomaterials in antimicrobial applications. The results support the development of multifunctional ICT-based nanohybrids with reduced reliance on metallic silver, addressing growing environmental and regulatory concerns
Melatonin-enriched merlot wine: chemical profile in early aging
No full textMerlot wine samples enriched with three melatonin concentrations
added during the pre-fermentation phase of vinification were analyzed using
OenoFoss and spectrophotometry for chemical parameters and total flavonoids.
Melatonin did not affect alcohol, residual sugars, density, acid balance, or
microbiological stability, indicating that fermentation remained unchanged.
Beneficial effects were observed in the phenolic profile, flavonoid levels, and
color attributes. These results suggest that melatonin, especially at lower doses,
may promote synthesis and stabilization of phenolic compounds and pigments,
enhancing color retention and overall sensory and chemical quality during early
aging
Biomarkers for Tracking Organic Matter Maturity in Therapeutic Muds (Peloids): A Comparison of Natural and Spa-Scaled Systems
No full textPeloid maturation is governed by geological settings, duration of water–sediment interaction (microbial reworking), and thermomineral water properties, with molecular distributions providing insights into transformation mechanisms. To assess site-specific biomarker maturity, geochemical parameters were applied to five Serbian therapeutic muds, including spa peloids (Bujanovac, Jošanica, Kanjiža) and natural systems (Vrujci, Rusanda). Mineralogy was determined via X-ray diffraction, and organic matter (OM) was characterized by gas chromatography–mass spectrometry of n-alkanes, steranes and hopanes. Samples are mostly clay-rich, providing favorable catalytic conditions for biomarker transformations. Bujanovac shows a higher plant OM signature (n-C29 maximum) and elevated biomarker maturity (high Ts/Tm, near-equilibrium C29 S/(S + R)), likely inherited from volcanically influenced source material. Jošanica exhibits high CPI but low Ts/Tm and C29 S/(S + R), indicating largely immature OM despite four years of spa aging. Kanjiža shows unexpectedly high apparent maturity after one-day aging, with a pronounced UCM and C31 S/(S + R) (0.58), consistent with incorporation of migrated petrogenic hydrocarbons. Vrujci displays coherent maturity due to prolonged water–sediment interaction, clay-rich mineralogy, extended aging, and regional geothermal gradients. Rusanda exhibits decoupled parameters (CPI 3.91, C29 S/(S + R) 0.69), indicative of hydrocarbon overprinting. Overall, integrating biomarker geochemistry with mineralogy, depositional context, and local thermal/geological conditions provides a robust framework to evaluate peloid maturation
ROS-mediated antiproliferative effects of dihydrotestosterone-derived ferrocene–steroid conjugates toward human cancer cell lines of variable androgen dependence
No full textFerrocene appendages often endow organic scaffolds with reactive-oxygen-species (ROS)-mediated cytotoxicity, yet ferrocene–androgen conjugates remain somewhat poorly explored, especially those linked at the steroid A-ring, known to modulate androgen receptor (AR) binding. Three C-2-substituted ferrocene–steroid conjugates derived from dihydrotestosterone (DHT) – the most potent human androgen – were synthesized; the structure of 1 was confirmed by single-crystal X-ray crystallography. Antiproliferative activity was quantified in AR-positive (LNCaP, OVCAR-3) and AR-negative (PC-3) cancer cells and in non-malignant MRC-5 fibroblasts. The balance of androgenicity and inherent cytotoxicity brought about by the presence of ferrocene proved adequate, as all conjugates acted in an antiproliferative manner toward the two hormone-responsive cancerous cell lines. Conjugate 2 (2α-ferrocenylmethyl-DHT) was the most potent analogue, inhibiting OVCAR-3 growth with an IC50 = 2.8 μM and a selectivity index of 3.0 relative to cisplatin. In OVCAR-3 cells, 2 triggered S-phase arrest, a 21-fold rise in intracellular iron, and ROS-dependent loss of viability; co-treatment with N-acetyl-l-cysteine, but not the caspase inhibitor Ac-DEVD-CHO, rescued cells. In multicellular tumor spheroids, 2 disrupted spheroid integrity (IC50 = 14 μM). These findings indicate the potential of A-ring substituted androgen-ferrocene conjugates as antiproliferative agents for hormone-dependent cancers, with 2 emerging as a promising candidate that surpasses cisplatin in potency and appears to act through a distinct mechanism
Improving electrochemical aptasensor sensitivity for Bacillus cereus spore detection in food safety applications
No full textRapid detection of Bacillus cereus spores is essential for preventing food contamination and spoilage. Many existing methods detect B. cereus vegetative cells rather than spores and cannot be applied directly to foods. Here, we present a combination of aptamers targeting different moieties on the surface of B. cereus spores with rapid electrochemical detection. When DNA aptamers, previously selected for B. cereus spores, were immobilized on screen-printed gold electrodes, they exhibited higher binding capacity than individual aptamers, suggesting a synergistic effect. Additionally, the mixture of rhodamine-labelled aptamers enabled spatial fluorescent visualization of the B. cereus endospore structure, confirming the increased binding efficiency. The electrochemical aptasensor based on three aptamers exhibited a wide dynamic range (102–107 CFU/mL) and low limit of detection (∼1 CFU/mL) using just 15 μL of sample. Validation in spiked salad, using direct spore sensing in rinse water and comparison with the culturing method, confirmed its sensitivity and specificity. These combined aptamer approaches, achieving rapid (15 min) and single-step detection may also be suitable for detecting other foodborne pathogens.Supporting information: [https://cer.ihtm.bg.ac.rs/handle/123456789/9025
Potential pandemic: Biothermodynamic analysis of the yellow fever virus-host interaction
No full textThe yellow fever virus can infect several kinds of host cells in the human organism. However, liver damage dominates during yellow fever, due to lysis of hepatocytes and accumulation of virus particles inside them. Thermodynamic driving force for multiplication of viruses provides the answer to why the liver is among the most severely damaged organs during yellow fever, while less damage occurs in kidneys, spleen and bone marrow. The physicochemical perspective on pathogenesis indicates the most thermodynamically and kinetically favorable host cells for multiplication. The mechanistic model developed in this way relates the driving force as the fundamental physical force and pathogenesis as a biological phenomenon
History (and Prehistory) of Pathogenic Cases of Teeth: Relevance to Medicine, Veterinary Science, and Nutrition of Living Organisms on Earth
No full textThe history (and prehistory) of pathogenic teeth cases, which is of
interest to both medicine and veterinary sciences, along with their connection to
the nutrition of living organisms on Earth, and the development of prosthetic aids
for replacing bone tissue, is rich in numerous facts and assumptions. Opinions
related to the development of modern diagnostic techniques for various organs and
the preservation of "traces" have also evolved. Parts of elephant dental materials
have been used for prosthetic aids in medicine and other fields. In the much more
recent era, spanning at least a century, significant changes have occurred with
the transition from metals to other materials of interest for dentistry and related
prosthetic materials. Many materials have been developed for creation of teeth
implants and various dentures, to replace natural teeth/bone material that is optimal
for bonding with soft tissue. For laser techniques, ranging from diagnostics to
the treatment of pathogenic conditions in soft and hard (bone) tissues, there
has been a constant progress, as lasers have become much more common part
of clinical practice, leading to a much higher number of interventions. Both the
techniques and simulations for various conditions have significantly increased. In
this paper, a selection of laser interventions is made for selected materials, such
as metals or materials closer to natural bone structures, associated with the teeth,
their overgrowth, filling materials, and mold creation. The study theoretically and
experimentally analyses selected types of materialy by lasers, and for a certain
number of cases, attempts modeling, as well as the application of diagnostic
methods for existing conditions or prediction of future cases. Special attention
is given to the trend of using lasers with short and long pulses, analyzing both
the positive and negative aspects of their interaction with tissues and prosthetic
materials
Advanced titanium implants: combating corrosion and infection with cutting-edge coatings
No full textThe presented research investigates the corrosion behavior of commercially pure titanium (cp-Ti) and amorphous calcium phosphate–chitosan (ACP@ChOL) coatings enriched with selenium on titanium in simulated body fluid (SBF). Using potentiodynamic polarization techniques, it was sought to derive essential corrosion parameters – corrosion potential, corrosion current density, breakdown potential, and passivation current. This study pioneers a comparative analysis of the corrosion stability of both samples. SEM/EDS analysis of surfaces pre- and postpotentiodynamic measurements offered insights into morphology and elemental composition. The aim was to elucidate the corrosion mechanism by integrating these techniques. Additionally, spontaneous corrosion behavior over 7 days, monitoring changes in open circuit potential, polarization resistance, and impedance were investigated. Furthermore, the antimicrobial efficacy of ACP@ChOL enriched with Se on titanium was assessed against Escherichia coli , Staphylococcus aureus , and Candida albicans , as well as in vitro release of Se. The presented study extends understanding, offering a unique perspective on the corrosion behavior and antimicrobial attributes of ACP@ChOL coatings enriched with Se on titanium. This composite material exhibits promise for medical applications, presenting an innovative avenue for addressing corrosion concerns and potentially reducing antibiotic reliance
Imipramine solubility-pH profiles: self-aggregation vs. common-ion effect
No full textBackground and purpose: The pH-dependent solubility of imipramine, a tricyclic antidepressant, and its hydrochloride salt was investigated in phosphate buffers and chloride-containing aqueous media using the pH-ramp shake-flask method. It was reported that aggregation of imipramine in acidic media and its partial degradation in alkaline media complicate the determination of its solubility. This was further investigated with modified methods. Experimental approach: For imipramine solubility studies, the computer program pDISOL-X was used to design experiments, process data, and refine the equilibrium constants. Isolated solid precipitates under various conditions were characterized using thermogravimetric analysis, differential scanning calorimetry, powder X-ray diffraction, and elemental analysis. The critical micelle concentration of imipramine hydrochloride was determined in 0.10 mol L-1 NaH2PO4 and in 0.15 mol L-1 NaCl by conducto-metric titrations. Key results: A detailed analysis of imipramine pH-solubility profiles reveals complex equilibria in the aqueous phase, as well as various solid-phase transformations. Intrinsic solubility of imipramine, solubility products of imipramine hydrochloride and imipramine phosphate salts, and aggre-gation constants (trimer, heptamer, and cationic complex with phosphate ions) were determined. Solid state characterization results are in accordance with pDISOL-X analysis. Conclusion: These findings, along with our previous solubility studies of desipramine and nortriptyline, suggest that even subtle structural variations can lead to significant differences in the aqueous media behaviour of tricyclic antidepressants. This type of information can be valuable in the early stages of drug discovery, in formulation optimization experiments, as well as in in vitro and in vivo studies.This research aligns with the United Nations Sustainable Development Goal 3 - Ensure healthy lives and promote well-being for all at all ages.Supplementary material: [https://cer.ihtm.bg.ac.rs/handle/123456789/9129